The efficient introduction of cables into an underground conduit, which may extend for several thousand feet, has long been a problem. Such conduits are often designed to hold a plurality of cables such as for use in the telecommunications industry. The placing of the first cable in the conduit is the least problematic. Traditionally, the cable is inserted by means of a pushing device, and the insertion may be assisted by a flow of air which is blown into the conduit.
Because the first cable will generally undulate within the conduit, a second cable cannot be readily positioned in the conduit by the same pushing/air blowing procedure. Rather, a pulling mechanism, usually in the form of a tape, must be positioned in the conduit. Then the second cable is attached to the pull tape which is then used to attempt to pull the second cable into the conduit.
While the pull tape is somewhat easier to insert, because of its flexibility compared to a cable, such still represents a somewhat complex procedure. In some instances where the first cable in the conduit is relatively straight, with only minimal undulations, it may be possible to use the air blowing process to insert the tape. However, in the usual situation, the existing cable is undulating in the conduit rendering it more difficult to insert the tape. Moreover, if the tape can be successfully inserted by conventional means, it is often wrapped several times around the existing cable making it difficult, if not impossible, to use the tape to pull another cable into the conduit.
As an alternative to blowing in the pull tape, a rodder system may be utilized. In this system, a relative rigid rod is inserted and finds it way through the cable(s) to the other end of the conduit. Then the pull tape is attached to the rod and the rod is pulled back. These systems are quite expensive to employ as they require multiple, labor intensive, time consuming passes through the conduit using expensive equipment, and even then these systems are normally only effective over short distances.
The need exists, therefore, for a viable alternative to the existing systems when attempting to install an item into a conduit which is already carrying an undulating cable.